spree carb jetting

[Provost33]

OK.. I have a 85 spree with a 48mm bbk and a 24mm carb. (Wanted a 21mm carb but was hoping to make this work). Started with the 105 main jet and it ran great until half throttle to wot and it starts to bog until it dies.. if you give it half throttle until 20mph and then opened it up it was ok.. I figured the main jet was to big so I have tried a couple smaller jets... does anyone know what else I could do.. I have messed with the needle and air screw but it idles great and runs good until wot at lower speeds.... only thing I haven't done is go with a bigger main jet because I figured by bogging down that means its to rich... thanks

[Wheelman-111]

Greetings:

What temps are you seeing? What color spark plug?
It may be that even with generous 48mm gulps, the low-revving Spree design can't maintain enough vacuum in that big carb throat to pull from any size of main jet. Putting a more restrictive filter might help - or just oil whatcha got. In any case, 105 sounds a bit small for that size carb if anything, but keep in mind I have NO Spree tuning experience.

In general if the mixture becomes non-combustible with the throttle wide open but she fires again if you close the throttle a little, you're too lean, not rich. The plug color and temps would help decide that for sure. I really wouldn't ride that thing without a temp gauge anyway.

[Provost33]

Thanks, I don't have a temp gauge, I guess I should probably invest in one... as for the plug, it looks pretty good but I usually get it up to speed and open it up then kill it. So when I kill it its running good and not bogging... I'm going to get a temp gauge and bigger jets and anothee fresh plug and start over

[Provost33]

And oil I'm running 50:1 plus pump... I want to get rid of the pump but I don't have any plug for it... thought about running the line from the pump back to the oil tank or I wonder if the pump would seize up if it wasn't pumping anything and removw the lines

[Wheelman-111]

Greetings:

50:1 plus the pump is WAY too much oil. Most likely this is making it lean on fuel, regardless of the jet size, which I believe is small anyway. You run a pretty big risk operating with this setup. While the pump is running, you need maybe 70:1 or so, Tops. I ran an Aero big block using 90:1 for a long time.

The pump can be set up with a loop of line to feed back to the pump temporarily, but it's better to eliminate it and the drag it puts on the crankshaft altogether. Buy a pump plug or make one. Then use 32:1 premix alone. TrailTech makes an affordable temp gauge if you don't want to spring for Graphite's offer.

[patthesoundguy]

What are you running for a pilot maybe its too lean on the bottom end.

[paulpauly7]

pull the pump out grind the gears off the end of the shaft and refit .